Field of the Invention
Embodiments of the invention relate to an autostereoscopic display and a method for driving the same.
Discussion of the Related Art
As stereoscopic image reproduction technology is applied to display devices, such as a television and a monitor, with the development of stereoscopic image display technology, now is the age in which people can easily view three-dimensional (3D) stereoscopic images even at home. A 3D display may be classified into a stereoscopic display and an autostereoscopic display called a glasses-free 3D display. The stereoscopic display displays a parallax image between the left and right eyes on a direct-view display or a projector through changes in a polarization direction of the parallax image or in a time-division manner and thus implements a stereoscopic image using polarization glasses or liquid crystal shutter glasses. The autostereoscopic display implements the stereoscopic image by installing an optical part, such as a parallax barrier (hereinafter referred to as “barrier”) and a lenticular lens (hereinafter referred to as “lens”), for separating an optical axis of the parallax image in front of or behind a display screen.
Not only a technology for forming the barrier or the lens using a fixed optical film but also a 3D cell implementing the barrier and the lens by adjusting a voltage applied to a liquid crystal layer have been recently developed. The 3D cell is defined as an optical part for separating optical axes of left eye image data and right eye image data of 3D image data using an electrically controllable liquid crystal layer. A viewer sees pixels, on which a left eye image is displayed, through his or her left eye and sees pixels, on which a right eye image is displayed, through his/her right eye using the 3D cell, thereby feeling binocular disparity. The 3D cell may be implemented as a switchable barrier or a switchable lens. The switchable barrier and the switchable lens were disclosed in U.S. patent application Ser. No. 13/077,565 (2011 Mar. 31) and Ser. No. 13/325,272 (2011 Dec. 14) corresponding to the present applicant, and which are hereby incorporated by reference in their entirety.
When DC voltage is applied to liquid crystal molecules for a long time, the liquid crystal molecules are degraded due to an unwanted electrochemical reaction of the liquid crystal molecules, and image sticking is generated. To prevent the problems, a liquid crystal layer of a liquid crystal display and a liquid crystal layer of the 3D cell are driven using an alternating current (AC) voltage of which a polarity is periodically inverted. For example, a positive voltage is applied to liquid crystal cells in odd-numbered frame periods, and a negative voltage is applied to the liquid crystal cells in even-numbered frame periods. However, when the liquid crystal layer of the 3D cell is driven using the AC voltage, a kickback voltage varies depending on a polarity of the voltage applied to the liquid crystal layer of the 3D cell in the same manner as the liquid crystal display. Therefore, a flicker may appear in a cycle in which voltages of the same polarity repeat. If the flicker of the liquid crystal display is synchronized with the flicker of the 3D cell, an intensity of the flicker may further increase. Even if an image displayed on the liquid crystal display has the excellent display quality, a stereoscopic image may be degraded due to the flicker of the switchable barrier or the switchable lens.